Process of treating wood



UNITED STATES PATENT OFFICE.

ALEXANDER E. TWOMBLY, OF'NEW YORK, AND ANDREAS ll LONDIN, OF BAYSIDE, NEW YORK, AND ROBERT A. MARE, OF NORFOLK, VIRGINIA, ASSIGNORS, BY MESNE ASSIGNMENTS, TO AMERICAN BALS-A COMPANY, INC., A CORPORATION 01 Patented Nov. 15, 1921.

NEW YORK.

PROCESS OF TREATING WOOD.

1,396,899. Specification of Letters Patent.

No Drawing.

To all w from. it may concern Be it known that we, ALEXANDER H. TwoMnLY, of New York, N. Y., ANDREAS P. LUNDIN, of Bavside New York, and ROBERT A. Mann, of Norfolk, Virginia, citizens of the United States, have invented certain new and useful Improvements in Processes of Treating Woods, of which the following is a description .in such full and clear terms as will enable any person skilled in the art to which it pertains tomake and use the same.

Our invention .relates to a process of seasonin wood and at the same time preserving 1t according to which the wood in any condition, whether reen or dried, may be season-ed to any egree of moisture wished, and the wood will be preserved thereafter in this seasoned state regardless of weather conditions to which 'it may be exposed. The process also afi'ects the removal of constituents in the wood which promote decay and prevents dry rot.

Heretofore it has been proposed to pre serve wood by impregnating it with heavy hydrocarbons. Some of these processes have been partially successful, but they have failed of complete success with some kinds of woods. The object 'of our invention is to provide a process by which any kind of wood may be seasoned to any desired degree of moisture without causing checking or injury to the fibers of the wood and may be preserved in this condition bymeans of an encysting .of its fibers with a substance which renders it substantially water roof. ()ur process,v furthermore, results in t e re moval from the wood of those constituents thereof'which if :allowed to remain in the wood would promote decay.

According to our invention, we first subject the wood to be treated to a preliminary steaming or humidifying process, carried on preferably in a closed retort. The process is egun at a comparatively low temperature and the temperature in the retort is gradually raised by the action of steam heating coils' or other, heating means. The air with--" in the retort is always maintained in a condition of highhumidity, near the point of saturation, vapor or steam jets being discharged into the retort to maintain the proper humidity, water jets being admitted with the steam to this end, if necessary.

Application filed January 10,1917. Serial No. 141,531.-

During this humidifying process moisture is absorbed by the wood, causing it to swell, dissolving to some extent intercellular matters contained in the wood, such as gums, albumins, sugars, starches and acids. By this treatment, also the cells of the wood are put into better condition to receive and absorb the waterproofing compound without injury, and we believe that the cell walls are rendered softer and more porous and elastic so that in the subse uent treatment of the wood hereinafter described moisture contained in the cells may be driven off without disadvantageous effects on the cell walls or the fibers of the wood. Steaming or humidifying should be begun with the wood at comparatively low temperature and maintained at the low temperature for some length of time in order that the albumins contained in the wood ma be dissolved b the moisture absorbed by the wood before t e temperature is reached at which albumin coagulates. The temperatures at which the steaming or humidifying process will be carried on and the length of time during-which it will be continued vary according to the wood and its condition, andthe processcontinues preferably until moisture has netrated to the very center of-the wood. ith an ordinary ture in the retort being graduated progressively fromsay 100 to 190 F. with the humidity up to 1( )0% during the first part of the time and then-gradually lowered after the humidity has penetrated to the center of the wood. I

I After the wood has been treated as above described it is submerged in a hot bath of a waterproofing compound the boiling point of which is in excess of that of water, the wood being placed in this bath preferably while it is yet warm from the saturation or humidifying process. This waterproofing comound may be of various com ositions, but it is preferably composed of mixture of hydrocarbons, such as asphalt and paraffin, as described in the Broady ap lication for Patent Serial No. 58,232, filed ctober 27th, 1915, or a mixture of parafiin and na hthalene, such as is described in the Marr atent No. 1,023,784, or a mixture of aratfin and rosin, such as is described in the arr Patent Reissue No. 13,952. We do not, however, wish it to be understood that our invention is limited to the use of these particular substances.

The temperature at which this bath is maintained is preferably somewhat in excess of the boilin point of water, and about 220 to 250 F. hen the wood is submerged in this hot bath the moisture in the wood passes out from. the wood in the form of vapor, carrying with it many of the intercellular constituents of the wood which have been dissolved in the saturation or humidifying process. The vapor passes out, rising in bubbles through the bath, the hydrocarbon mixture enters the cavities of the wood and encysts the cell walls thereof.. It a thorough encysting of allthe Wood cells is desired the process is continued until cessation of the bubbling off of vapor indicates that the moisture has been wholly expelled from the wood, but the process may be continued for as long or as short a time as is desired according to the degree of moisture which it is desired to retain in the wood and according to the thoroughness with which it is desired to encyst the cells.

Preferably we subject the wood in the bath to the process set out in the Broady application, Serial No. 91,109, filed April 14th, 1916, that is to say, we lower the temperature of the bath after the wood has been in it for some time, with the result that as a partial vacuum is produced in the wood by the condensation of vapor within it the vacuum assists capillary action in drawing the hydrocarbon in to the passageways of the wood; and we follow thls cooling by a subsequent raising again of the temperature before removing the wood from the bath, by means of which the vapor remaining in the wood is expanded again, and a portion of the hydrocarbon which has penetrated is driven out. By means of this cooling and reheating of the bath it is found that a better encysting action is attained, but it will be understood that this is no essential part of our invention.

It will be understood that the duration of this submersion in the bath, like the duration of the steaming or humidifying process, depends upon the character and condition of the wood. Woods that contain a large percentage of moisture require only a short treatment in order to be thoroughly encysted with the hydrocarbon mixture. Such woods are birch, pine, spruce and balsa. lVoods which contain less moisture and are of a denser texture, such as mahogany, oak, etc., require a longer treatment in the steam or humidifying bath and a longer continuance of the lower temperature in said bath since sudden high temperatures have a tendency to cause checking.

\Vood treated by this process will be found to be substantially waterproof, and it therefore remains indefinitely in the seasoned state to which it is brought by the process. The process also has the advantages over other seasoning processes that it results in the removal from the wood of intercellular matters, such as albumins, sugars, etc., which by their presence in the wood tend to promote decay, and that the temperatures to which the wood is subjected in this process destroy the spores in the wood which might otherwise cause dry rot, the encysting of the cells preventing subsequent entry of such spores. Furthermore, the process is much shorter than previous seasoning processes.

What we claim is The process of treating wood which consists in first humidifying it by exposure to steam the wood being maintained at temperatures above 100 F. and below212 Fahrenheit, and then subjecting it to a bath of a water-proofing substance heated to a temperature equal to or greater than 212 F ahrenieit.

In testimony whereof we have hereunto signed our names in the presence of witnesses.

ALEXANDER H. TW'OMBLY. ANDREAS P. LUN DIN. ROBERT A. MARR.

JOHN FAnRAs. 

